Means and method of removing cores



12, 1953 T. c. BANNoN 2,638,323

MEANS AND METHOD OF REMOVING CORES Filed Dec. 3, 1948 will ` E; QQ@ aww ATTORN EY Patented May 12, 1953 MEANS AND METHOD OF REMOVING CORES Thomas C. Bannon, Altadena, Calif., assignor of fifty per cent to Lloyd Spencer, Los Angeles,

Calif.

Application December 3, 1948, Scrl No. 63,245

(Cl. Z55-1.8)

14 Claims. 1

In core drilling, particularly the drilling of shafts several feet in diameter, it is the practice to employ an annular drill or core drill. The annular cutting end may contain diamond or other hard cutting material, or more frequently in the drilling of large bores, chilled shot is fed to the cutting surface.

The core drill or cutter is several feet in height to accommodate the central core formed as drilling proceeds. The core drill is driven by a central shaft from a drive unit immediately above the core drill, or more commonly by means of drill pipe which extends to the surface of the shaft and which is rotated by a surface rig similar to the drilling rigs employed in oil well drilling.

Water is introduced through the string of drill pipe to cool the drill and to carry away cuttings, usually a collector is mounted on the core drill for this purpose.

After drilling has proceeded a distance determined by the length of the core drill, the core drill is removed and a core extractor barrel is lowered over the core. Conventional core barrels are provided with slips or wedging devices to engage the core near its base. The core barrel or extractor is preferably suspended from drill pipe so that upon engaging the core a substantial upward strain, calculated to part the core by tension, may be applied. In firm rock of high tensile strength twenty tons or more is required to break a core of thirty inches in diameter weighing approximately four to eight tons. In attempts to core drill larger bores, lateral wedging of the core is resorted to in attempt to break it loose; still further, a dynamite charge may be placed on one side to force the core laterally. These methods of breaking the core are haphazard and often result in spauling or breaking the core into fragments which cannot be removed by the core extractor barrel but must be removed piecemeal by dangerous and costly methods. In some cases workmen are lowered into the borehole to wedge the cores loose and/or retrieve core fragments.

I seek by means of my invention to avoid and eliminate the difficulties which have been previously encountered in the removing of cores, particularly cores of large diameter. Accordingly then, included in the objects of my invention are:

First, to provide a means and method of removing cores whereby the core is severed from the formation by a clean transverse break with a minimum of spauling and without application of excessive tensional loads, and which minimize the .need for Workmen to descend into the shaft.

Second, to provide a means and method of removing cores which utilizes a controlled explosive force concentrated in a predetermined plane but distributed evenly about the periphery of the core.

Third, to provide a means and method of this class which in one form employs a specially arranged shaped explosive charge of annular form, in another form a circumferential series of shaped charges, and in still another form a series of bullets all directed radially inwardly.

Fourth, to provide a means and method of this class wherein the explosive means for severing the core is incorporated in an explosive resisting body carried by a core engaging structure or core extractor barrel whereby the core may be engaged and placed under moderate tension while simultaneously subjecting the core to a directed explosive force.

With the foregoing and other objects in view as may appear hereinafter, reference is directed to the accompanying drawings, in which:

Figure 1 is a partial elevational partial sectional view of a core extractor barrel incorporating my invention and shown suspended from a drill-pipe string within a shaft in which remains an upstanding core.

Figure 2 is a typical transverse sectional view of the body structure and showing an explosive charge in the form of an annular ring carried thereby, the view being taken along the line 2 2 of Fig. 3.

Figure 3 is a fragmentary sectional view thereof taken in the plane 3 3 of Fig. 2, showing the explosive charge and a detonating means therefore.

Figure 4 is a fragmentary sectional view through 4 4 of Fig. 3 showing the detonating means and the lead wires thereto.

Figure 5 is a fragmentary internal view of a modified form of explosive device, wherein projectiles are employed to effect cleavage of the core.

Figure 6 is a fragmentary sectional view thereof taken through 6 6 of Fig. 5.

Figure 7 is a fragmentary internal View, similar to Fig. 5 showing a further modified form of explosive device in which individual shaped charges are employed.

Figure 8 is a transverse sectional view thereof taken through 8 8 of Fig. 7.

Reference is rst directed to the construction shown in Figs. 1 through 4. A core extractor barrel I in the form of a steel sleeve adapted to encompass a core A, is suitably supported as by a spider frame 2 from the lower end of a drill-pipe string 3. The lower portion of the core extractor barrel is provided with internal downwardly converging wedging faces E on which ride wedges or slips 5. The slips are arranged to engage the sides of the core adjacent its lower or attached end. The slips may be attached to rods 6 extending above the core barrel and accessible in case it is desired to remove the core extractor barrel without engaging the core.

The lower end of the core extractor barrel is adapted to receive a ring body I, below the ring body is an annular guard head 8, which may be provided with cutting teeth 9 to aid in bottoming the core extractor barrel. The core barrel extractor, ring body and guard head are preferably provided with stepped interlocking axial ends so disposed that the guard head and core extractor barrel tend to support the ring body against radially outward forces. Axially directed bolts I join the guard head and ring body to the core extractor.

The ring -body 'I is provided with an internal channel II intersected at intervals by pairs of small radially outwardly extending bores I2. The channel `I I is adapted to receive an explosive cartride I3. The cartridge I3 includes a bendable tube or shell le having an essentially crescent shaped cross section, the convex side being semicircular and the concave side being V-shaped to form a longitudinal V-groove |15. The shell may be extruded or otherwise formed of copper, lead or other soft metal and is filled with a detonatable explosive material I6 such as TNT, PETN, Balistite, or other material vcapable of high velocity detonation.

; yThe cartridge may be in the form of an elongated tube either straight or curved in coil form. A length is provided which forms a loop Within the channel II the ends of which confront. Betweenthe confronting ends of the cartridge there is placed a detonating unit I'I, comprising one or more electrical detonators I8 within a circular tube I9. Adapter fittings 20 having tubular ends to fit the tube I3 and crescent apertured to conform to the cartridge shell I4 join the ends of the shell Irl to the ends of the tube I9 isoform a closed circle. Lead wires 2| extend radially from the tube IS and are adapted to nt in a groove extending upwardly across the radially inner face of the ring body. f

- The lead wires enter a conduit 22 provided within the core extractor barrel and terminate ina suitable connector unit 23 mounted in the spider frame 2 and exposed to the interior of the drill-pipe string 3. The circuit to the detonators I3 may be completed through a contacter 24 lowered on a suitable conductor cable 25.

The cartridge I3 is held in place with its V- groove I directed radially inwardly by means of tie wires 23 threaded through the radial bores I2. Operation of the structure shown in Figs. 1 through 4 is as follows: 1 The-core extractor barrel I is lowered over the core A. If necessary it is rotated by the drillpipe string 3 to insure .seating of the core extractor barrel. The slips arranged to wedge when the core extractor barrel is raised so that a rm grip is obtained on the core. The cartridge I3 is then fired.

By reason of the V-groove I5 as much as forty to fty percent of the explosive force is directed radially inwardly in the plane passing .through thecenter of the cartridge. As a consequence, a relativelysmall charge, insumcient to damage the ring body 'l is sufcient to `sever the core in this plane..

rbody ring 2| is provided with radially outwardly directed cavities equally spaced about its inner side. These cavities are threaded to receive gun radially` inwardly directed barrels 22 and, at the breach ends `of said barrels, cartridge chambers l23. rI'he gun barrels 22 receive bullets 24 whereas explosive cartridges are provided in the chambers 23. A rupturable seal disk 25 is provided at the breach end of each gun barrel to exclude moisture. f

The axially upper side of the ring body 2| is provided with a circular groove which receives a detonating element 26, connected with an appropriate electrical detonator, not shown. A detonator passage 2 1 leads from the circular. groove to each cartridge chamber 23. A suitable sealing gasket, not shown, is interposed between the axially upper end of the ring body and the core extractor barrel to exclude moisture.

Operation of the construction shownin Figs. 5 and 6 is essentially the same as in the previously described structure. The bullets several inches radially inwardly into the core A and exert a splitting forceout-of-proportion to In addition the explosive actual penetration. cartridges preferably have excess energy which backs the bullets as they penetrate with high pressure gas tending to part .the core.

Reference is now directed to Figs. '7 and 8. In

the construction here shown a body 3| is provided which is similar tothe body 2|. Thebody 3| is provided with radially inwardly directed cavities 32 which are capped by cone members33 and filled with detonating charges 34. Flame or detonating passages 35 communicate with an anelv nular groove in the axially upper face of the body 3| which groove contains. a detonator cord 33v such asaPETN cord. l y

Operation of this arrangement involves vernployment of the radially inwardly directed jets produced by Vdetonation of the several charges 34.

concentrated by the form of the cones 33.

It should be observed that the ring bodies 1, 2| and 3|, particularly the latter two, lmay be made in arcuate sections rather than one piece.

My method of removing cores consists essentially in directing radially inwardly from an explosive resistant body an explosive force calculated to vsever a core embraced bythe resistant body; and further to direct-such force while subjecting the core to tensional strain.

Having thus described certain embodiments of my invention, I do not desire to be limited there-l to, but intend to claim all novelty inherent lin the appended claims.

-I claim: u

l. In the art of bore drilling whereinan. annular core bit is employed to drill a section of hole in which remains a central core, the method of removing such cere, characterized by: directing explosive charges radiallyinwardly at the base of a core while protectingthe surrounding wall from the effect thereof; and simultaneously placing tensile strain on .said core, thereby to sever, said core acrossits base 'topermitremovaL penetrate`V 2. In the art of bore drilling wherein an annular drill is employed toform a section of hole in which remains a central core, an apparatus for severing said core, comprising: a core extractor barrel adapted to iit over said core; core catchers within said extractor barrel for engaging said core; an annular explosive resisting structure below said core catchers, said structure defining at least one explosive receiving recess directed radially inwardly; an explosive charge in said recess; and means for igniting said explosive charge to produce a radially inwardly directed explosive impact against said core to split the same transversely.

3. In the art of bore drilling wherein an annular drill is employed to form a section of hole in which remains a central core, an apparatus for severing said core, comprising: an annular explosive resisting structure adapted to t around said core and be disposed adjacent the base thereof, said structure deiining at least one explosive receiving recess directed radially inwardly; an explosive charge in said recess; and means for igniting said explosive charge to produce a radially inwardly directed explosive impact against said core to split the same transversely.

4. In the art of bore drilling wherein an annular drill is employed to form a section of hole in which remains a central core, an apparatus for severing said core, comprising: an annular explosive resisting structure adapted to t around said core and be disposed adjacent the base thereof, said structure defining a radially inwardly directed circumferentially extending channel; an explosive charge in said channel; and means for igniting said explosive charge to produce a radially inwardly directed explosive impact against said core to split said core transversely in substantially the plane of said channel.

5. In the art of bore drilling wherein an annular drill is employed to form a section of hole in which remains a central core, an apparatus for severing said core, comprising: an annular explosive resisting structure adapted to fit around said core and be disposed adjacent the base thereof, said structure defining a radially inwardly directed circumferentially extending channel; an explosive charge in said channel, the radially inner side of said charge having a circumferentially extending V-groove thereby to produce a concentrated radially inwardly directed explosive force calculated to split said core in the plane of said explosive charge; and means for detonating said charge.

6. In the art of bore drilling wherein an annular drill is employed to form a section of hole in which remains a central core, an apparatus for severing said core, comprising: an annular explosive resisting structure adapted to t around said core adjacent the base thereof, said structure defining a plurality of radially inwardly directed explosive charge cavities disposed substantially in a common plane; explosive charges in said cavities; and means for igniting said explosive charges to produce radially inwardly directed impacts against said core in said common plane to split said core transversely.

7. In the art of bore drilling wherein an annular drill is employed to form a section of hole in which remains a central core, an apparatus for severing said core, comprising: an annular explosive resisting structure adapted to t around said core adjacent the base thereof, said structure defining a plurality of radially inwardly directed explosive charge cavities disposed substan- 6. tially in a common plane; explosive charge units in said cavities, said explosive charges having conical recesses in their radially inward sides to produce a radially inwardly concentrated explosive impact against said core thereby to split said core in said common plane; and means for igniting said explosive charge units.

8. In the art of bore drilling wherein an annular drill is employed to form a section of hole in which remains a central core, an apparatus for severing said core, comprising: an annular explosive resisting structure adapted to t around said core adjacent the base thereof, said structure deiining a plurality of radially inwardly directed explosive charge cavities disposed substantially in a common plane; explosive charge units in said cavities, each explosive charge unit including a cartridge chamber and a radially inwardly directed barrel, an explosive cartridge in said chamber and a bullet in said barrel; and means for igniting said cartridges to drive said bullets radially inwardly into said core thereby to split said core in said common plane.

9. An apparatus for removing cores formed in bores by previous operation of an annular core drill, comprising: an annular explosive resisting structure adapted to t around a core and having an internal, circumferential channel; an explosive charge extending along said channel and having a circumferentially extending radially inwardly directed V-groove in its inner side; and means for detonating said charge to produce an explosive impact concentrated in the plane of said charge.

10. An` apparatus for removing cores formed in bores by previous operation of an annular core drill, comprising: an annular, explosive resisting structure adapted to fit around said core; explosive means carried by said structure and directed radially inwardly; said means adapted to concentrate and direct an impact force radially inwardly in a plane traversing said core, and at plurality of points about the periphery thereof; and an instrumentality for actuating said means.

1l. An apparatus as set forth in claim 10 wherein: said explosive means comprises a plurality of gun units each including a cartridge chamber, a radially inwardly directed barrel, an explosive cartridge in said chamber, and a bullet in said barrel.

12. An apparatus as set forth in claim 10 wherein: said explosive means comprises a plurality of gun units each including a radially inwardly directed barrel and an explosive charge having a conically formed recess at its radially inward end.

13. In the art of bore drilling wherein an annular drill is employed to form a section of hole in which remains a central core, an apparatus for severing said core, comprising: a core extractor barrel adapted to iit over said core; core catchers within said extractor barrel for engaging said core; an annular explosive resisting structure below said core catchers, said structure defining a radially inwardly directed circumferentially extending channel; an explosive charge in said channel; and means for igniting said explosive charge to produce a radially inwardly directed explosive impact against said core to split said core transversely in substantially the plane of said channel.

14. In the art of bore drilling wherein an annular drill is employed to form a section of hole in which remains a central core, an apparatus for severing said core, comprising: a core extractor amases References Cited in the le of this patent UNITED STATES PMENTS Number Name Date Gregory Dec. 28, 1915 Johnston u July 21, 1936 Frutchey Aug. 26, 1941 'Greulich Oct. 22, 1946 Davis et al Feb. 18, 1947 Williams June 14, 1949 Kaltenberger May 9, 1950 

